FIG. 1 shows a double flow steam turbine.
Double flow steam turbines 1 have a double flow rotor 2 that carries rotor blades 3, 4 and correspondingly stator blades carriers 5, 6 that carry stator blades 7, 8, defining two symmetrical steam paths 9, 10.
Steam is supplied via an inner casing 11a with an inlet belt 11b and passes through the steam paths 9, 10 to be then discharged through exhaust areas 13, 14; from the exhaust areas 13, 14 the steam S passes down through the condenser neck 15 to reach the condenser.
In some cases, the exhaust areas 13, 14 are too large; for example the steam turbine actual operation could occur with a lower mass flow than the design mass flow or with a higher backpressure than the design one.
In order to improve efficiency and maximise performance, the exhaust areas 13, 14 should be modified in order to match the actual capacity conditions of the condenser.